Apparatus for rolling sheet metal, and particularly cluster mills, require cooling of the sheet metal at the working roll pass; and the amount of colling required may be greater toward the center of the sheet than it is along the edges. Uniform cooling sprays that withdraw equal heat from the metal across its entire width are not satisfactory, therefore, because this results in cumulative buildup of heat at local areas, such as the center region of the sheet. Even distribution of temperature across the sheet is important to obtain a uniform gauge of the rolled sheet.
This invention provides rows of spray nozzles spaced from one another widthwise across the sheet. These nozzles are divided into groups. There is one group for cooling a zone extending along the center region of the sheet; and then there is another group of nozzles which cools zones on both sides of the center zone. The third group of nozzles cools zones which are nearer to the edges of the sheets and adjacent to the portions of the second zones which are remote from the center zone. Provision is made for operating more nozzles when the sheet is wider and fewer nozzles when the sheet being rolled is narrower.
The nozzles are adjustable to change the spray so that the rate of flow can be controlled and also the shape of the spray if desired. In the preferred construction of this invention, each nozzle has individual nozzle adjusting means operated by the controlled pressure of the coolant.
The nozzles are preferably of the type in which a tongue moves axially in an orifice. The surface of either the orifice or the tongue, or both, is tapered so that as the tongue moves axially with respect to the orifice, the cross section through which coolant can be discharged is increased or decreased.
By attaching the tongue of the nozzle to a piston or other movable wall, and then subjecting this wall to the pressure of coolant supplied to the nozzle, or to other controlled force, automatic adjustment of the nozzle discharge can be obtained as the result of variations in control pressure.
The nozzle adjustment can be effected in various ways depending upon whether the control pressure is used to move the piston or movable wall in a direction to increase the flow or decrease the flow of coolant. Apparatus for carrying out the invention in different ways will be explained in connection with the detailed description of the structure shown in the drawing.
Back pressure regulators or loaded valves (relief valves) are used in connection with the preferred pressure controls of this invention; and these back pressure regulators or loaded valves can be adjusted to control the pressure which is generated by a particular flow of coolant. Also pressure regulators upstream from the nozzles of individual groups of nozzles serve as regulators which influence the individual nozzle adjusting mechanisms.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.